Coaxial connector with an integral breakoff terminating resistor

ABSTRACT

A coaxial connector with an integral breakoff terminating resistor is especially suitable for CATV systems in which the coaxial connector includes a body having a first portion containing a contact spring and a second portion in which a terminating resistor is disposed. An interface portion between the first and second body portions is formed of material having a thickness substantially less than the thickness of material used in either of the body portions mentioned above. When it is desired to remove the terminating resistor as, for example, when connecting a subscriber&#39;&#39;s coaxial cable drop line to a CATV system, a relatively small amount of mechanical force applied to the second body portion causes the interface to rupture or fracture so that the second body portion along with the terminating resistor is readily removed, thus exposing the center conductor contact spring and a threaded area on the first body portion for mating with a companion connector that is attached to the subscriber&#39;&#39;s coaxial drop cable.

United States Patent [1 1 Cofiman [11] 3,768,063 Oct. 23, 1973 COAXIAL CONNECTOR WITH AN INTEGRAL BREAKOFF TERMINATING RESISTOR [76] inventor: "iifiHEi'gh G; Coff mEnT7 69 Bay Tree Lane, El Cerrito, Calif.

[22] Filed: Aug. 16, 1972 [21] Appl. No.: 280,969

Primary ExaminerRichard E. Moore Attorney-Paul D. Flehr et al.

[57] ABSTRACT A coaxial connector with an integral breakoff terminating resistor is especially suitable for CATV systems in which the coaxial connector includes a body having a first portion containing a contact spring and a second portion in which a terminating resistor is disposed. An interface portion between the first and second body portions is formed of material having a thickness substantially less than the thickness of material used in either of the body portions mentioned above. When it is desired to remove the terminating resistor as, for example, when connectinga subscribers coaxial cable drop line to a CATV system, a relatively small amount of mechanical force applied to the second body portion causes the interface to rupture or fracture so that the second body portion along with the terminating resistor is readily removed, thus exposing the center conductor contact spring and a threaded area on the first body portion for mating with a companion connector that is attached to the subscribers coaxial drop cable.

7 Claims, 3 Drawing Figures memes PAIENIEBum 23 ms 'SHEET 2 0F 2 1'. COAX-IAL CONNECTORWITH AN IN'IIIGRALv BREAKOFF TER'M'INA TING RESISTOR BACKGROUND OF THE INVENTION- In the cause of'construction andoperation of amodern Community Antenna Television (CATV) System, sometimes referredv to as Cable Television, it becomes necessary toterminate the unused subscriber coaxial connection provisions in the systems characteristic impedance. The characteristic impedance in a CATV system is typically 75 ohms. For example, all coaxial'cable, active and passive electronic devices used in the system are electrically designedto function with an impedance of 75 ohms.

A modern system is laid out and constructed with provisions: for a coaxial cable connection to each potential subscriber that is passed by the cable system. Such layout and construction practice is known in the industry as a, dedicated plant;

Upon completion of the system construction task it then becomes necessary to electronically and electrically balance the CATV system. It is at this time that the subscribers coaxial connection provisions must be terminated in the systems characteristic impedance. The subscriber coaxial connection provisions are usually located in a passive, electronic device known in the industry as adirectional tap. The coaxial connection provisions consist-of "a. threaded coaxialconnecton generally known in the CATV industry as: a- 6.61" chassis connector which is. integrated-into the directional tap housing. Directionaltaps are manufactured-with from two. to eight suchconnectors; with four connectors being the most commonly used configuration. There are various physical differencesinthe outward-appearance of the G61 type fitting; however, the portion of the fitting that is exposed" for connection to the subscribers coaxial drop. cable hasbeen standardized by the CATV industry. It is at the above described connector that the 75 ohm terminating resistor. is applied; In current industry practice, the terminating resistor is axially locatedin a threaded. housing in which the resistor leads become the center conductor and the housing the outer conductor. A terminating resistor assembly of the type just described is known in the industry as a TR59 terminator. The thread in the-TR59 terminator housing mates with the thread on the G61 chassis connector.

Subscriber coaxial-cable connections are made upon completion of the electricalbalancing-of the system, at which time the terminating resistor is removed from, and the subscribers coaxial drop cable is then attached to, the subscriber's coaxial connection.

As additional subscribers are connected to the system, more terminatingresistors are removed: with the subscriber's coaxialdrop cable replacing them. The unused subscriber coaxial cable connection provisions at the directional tap must remain terminated.

Considering that the average CATV system being constructedxconnect-s less than 25 percent of its potential customers, it becomes apparent that approximately 75 percent of' the directional tap subscriber coaxial connection provisions must remain terminated.

The cost associated with the termination requirements of a typi'cal'CATV system represents a considerable investment in facilities and labor to the owner of a CATV system.

Typical steps in the manufacture and installation of a C-ATV directional taps which contain the subscribers coaxial connection provisions include the following. First, in manufacturing the directional tap, usually after final assembly, a terminating device is attached to each subscriber coaxial connection for thepurpose of testing the performance of the directional tap assembly. The terminating device, in this. instance, consists of a suitable holder containing av terminating resistor. After testing, the terminating device, isremoved. Subsequently, when the directional taps are installed in the CATV system it is again necessary to install terminating devices as described earlier in this section.

It can be seen, therefore, that in the manufacture of directional taps forCATV systems and during the construction and balancing of the CATV system in which the directional taps are installed, considerable labor is requiredzin respect to the application, removal and general use of terminating devices.

In the event that should-it be desiredto disconnect a subscribers coaxial drop cable from. the CATV system at the directional tap connector, that connector may again be terminatedthrough theapplication of a TR59 terminator which was previously described.

BRIEF SUMMARY OF THE INVENTION Accordingly, it isan objectof this. invention to provide acoaxial connector, for use inconjunction with devices such asCA-TV directional taps, which connector is pre-terminatedin the characteristic impedance of the system in which it will be used.

It is another object of'this invention-toprovide such a pre-terminated coaxial connector'in whichthe terminating resistor is easily removed whendesired for the purpose of making subscriber connections to the CATV' system.

It is another object of this invention to-provide such a pre-terminated coaxial connector in which the connector will remain waterproof so long as the preterminatedresistor'has not been removed from the assembly.

It is another object of this invention to provide such a pre-terminated coaxial connector in which the connector, once the pre-terminating resistor is removed, will be compatible with mating connection devices commonly used in the industry.

Other advantages and objects of the invention will appear from the following description taken in conjunction-with the drawings.

In accordance withone embodiment of. the invention there is provided a coaxial connector for use in a signalv distribution system of the type having a transmission line extending from a directional-tap housing or junction box with the tap-housing mounting a plurality of coaxial connectors, each capable of being connected or coupled to. a'separate transmission line. Each coaxial connector comprisesabody with a first portion, a second portion and an interface portionintegral withand joining the second portion to=the first portion. The first portion mounts aninsulator and spring contact and the secondbodyportion mounts a terminating resistor having a pair of leads with one of the leads beingconnectedto the second body portion and'the other of the leads extending into the, first bod-y portion and being electricallyv connected with the spring contact therein. The interface portion of the body isformed of a material substantially thinner than the first and second body portions and is adapted to rupture or fracture upon the application of a deflecting force to the second body portion to thereby readily remove the second body portion along. with the terminating resistor contained therein.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to FIG. 1, there is shown a top plan view of a commonly used directional tap housing 11 which is partially broken away to illustrate the manner in which the coaxial connector with integral breakoff terminating resistors 12 through 15 are mounted in a wall 11a thereof. The directional tap housing 11 includes a cover 16 hinged by hinge assembly 17 and having means such as bolt 18 to secure the cover in place. Provision is made for mounting the tap housing to a messenger strand such as by a clamp assembly 19.

Referring to FIG. 2, which is a cross section taken 1 along the lines 22 of FIG. 1, there is shown in detail the coaxial connector with integral breakoff terminating resistor in accordance with this invention. There is provided a body 21 having a first portion 21a, a second portion 21b and an interface portion 210 joining the first and second portions together, The body portion 210 is hollow and contains an insulator 22 which surrounds, holds and locates a contact spring 23. The insulator 22 and hence the contact spring 23 are retained in the hollow body portion 21a by means such as a retaining lip 21d formed in the body portion 21a.

The portion 21b is also hollow and includes a hollow resistor lead receiving portion 21e having a sealed end. A terminating resistor 24 having leads 26 and 27 is disposed within the hollow body portion 21a. The lead 26 of terminating resistor 24 extends into the hollow lead receiving portion 21:: of the second body portion 21b. The lead 26 is mechanically and electrically connected to the body 21 through suitable connection to the body portion 21e. Suitable connection includes soldering or cold-staking the body portion 2le to the lead 26. Coldstaking has the advantage of avoiding any possible heat damage to the terminating resistor 24 which might:

occur during soldering. The other lead 27 of terminating resistor 24 extends into and makes electrical contact with the contact spring 23.

The first body portion 21a of the coaxial connector shown in FIG. 2 includes a threaded portion generally indicated by reference numeral 21f and includes a flange portion 21g. A washer28 is disposed between the flange portion 21g and the wall 11a of directional tap housing 11 in order to prevent the entry of water into the tap housing 11 and the coaxial connector is mounted to the wall 11a by a nut 29 screwed on to the threaded portion 21f.

The body 21 may also include a threaded portion generally indicated by reference numeral 21h for the purpose of receiving a mating connector 33 that is attached to the subscribers coaxial drop cable 32 when such drop cable is installed. A suitable thread protector 31 (plastic, for example) is disposed over these exposed threads 21h and can extend over and enclose the body portions 21b and 21e.

As shown in FIG. 2 and in accordance with the invention, the interface portion 21c of body 21 which joins the first body portion 21a to the second body portion 21b is substantially thinner than both body portions 21a and 21b. Also, in the specific embodiment shown in FIG. 2 this interface portion 21c is indicated as an indentation which can be a notch or groove formed therein and which is generally indicated by reference numeral 34.

Thus construction of the coaxial connector such as shown in FIG. 2 in accordance with this invention provides a coaxial connector which contains an integral terminating resistor for terminating the subscriber's coaxial cable connection provisions in a directional tap in the CATV systems characteristic impedance.

When it is desired to remove the terminating resistor from one of the coaxial connectors constructed in accordance with this invention, as for example, as in the case for a CATV system when a subscribers coaxial drop cable is to be attached to the coaxial connector, a lateral deflecting force is applied to the body portion 21b. This is illustrated in FIG. 1 by an arrow indicating force applied to the coaxial connector 13 shown in FIG. 1. This lateral displacement force can be applied, for example, by simply displacing the body portion 21b with a pair of pliers or other suitable device and results in rupture or fracture of the body 21 at the interface portion 21c between first body portion 21a and second body portion 21b. The presence of an indentation such as a notch or groove 34 facilitates such rupture or fracture. However, the second body portion 21b can be broken off at 21c even though the indentation at 34 is not present because the reduced cross-sectional area of the body material at the interface 210 will fracture at the point indicated as the groove numeral 34. With such fracture of the interface body portion 210, the second body portion 21b and the terminating resistor 24 are completely separated from the first body portion 21a. The force applied to the second body portion 21b also causes the thread protector 31 (if one is used) to be stripped off the threaded portion 21h of body 21 as well as withdrawing the lead 27 of terminating resistor 24 from the contact spring 23. This results in complete separation of the body portion 21b and the thread pro- 1 tector 31 along with the integrally contained terminating resistor 24 from the first body portion 21a. This is illustrated in FIG. 3. A coaxial cable such as subscribers coaxial drop cable in the case of a CATV system can then be connected to the coaxial connector at the directional tap from which the terminating resistor has been removed: Thus in FIG. 1 a coaxial cable such as the suscribers coaxial ,drop cable 32 having a mating coaxial connector 33 is shown connected to the directional tap. 11 through coaxial connector 12.

What has been described is an improved electrical coupling device or coaxial connector for signal distribution systems such as a CATV system in which the coaxial connector is pre-terrninated and in which the terminating means can be quickly and easily removed when it is desired to connect a subscribers coaxial drop cable to the directional tap. Incorporation of a coaxial connector with an integral breakoff terminating resistor into a directional tap at the time of manufacture leads to a saving in time and labor. Thus, upon completion of the manufacture of a directional tap it is not necessary to attach a separate terminating resistor to the directional tap in order to test it, since it already contains an integral terminating resistor. Subsequently, upon installation of a directional tap containing the coaxial connector described herein into a signal distribution system such as a CATV system, it is further not necessary to connect terminating resistors to all of the subscribers coaxial cable connectors of the system in order to test the system since each of the coaxial connectors already contain an integral terminating resistor. Also, since the first and second body portions including the hollow lead receiving portion 2le are integral with each other, and the end of the lead receiving portion is sealed, the pre-terminated coaxial connector is waterproof. After construction and test of a signal distribution system, when it is desired to connect the subscribers coaxial drop cables to the directional taps, removal of the integral terminating resistors is quickly and easily accomplished. Merely applying a deflecting force to an extending body portion of the coaxial connector ruptures or fractures the body at a specific location, thereby detaching a portion of the body and a terminating resistor contained therein.

While the invention has been described and illus* trated with respect to a specific embodiment, it should be obvious to those skilled in the art that various modifications may be made to the specific embodiment disclosed herein without departing from the true spirit and scope of the invention.

I claim:

1. A coaxial connector for use in a signal distribution system of the type having a transmission line extending from a directional tap housing with the tap housing mounting a plurality of coaxial connectors each of which is capable of being coupled to a transmission line, the coaxial connector comprising a body having a hollow first portion, a hollow second portion and an interface portion integral with and joining said second portion to said first portion, said interface portion being formed of material substantially thinner than said first and second body portions, a spring contact, an insulator surrounding said spring contact, said insulator and spring contact being disposed within said hollow first portion of said body, a terminating resistor having a pair of leads, said terminating resistor disposed within said hollow second portion of said body and one of said pair of leads being electricallyconnected to said second portion of said body and the other of said pair of leads extending into and being electrically connected to said spring contact.

2. A coaxial connector in accordance with claim 1 wherein said interface portion of said body has an indentation formed therein for facilitating rupture of said interface portion in response to mechanical deflection of said second portion of said body to separate said second body portion from said first body portion.

3. A coaxial connector in accordance with claim 1 wherein said interface portion of said body has a notch formed therein for facilitating rupture of said interface portion in response to mechanical deflection of said second portion of said body to separate said second body portion from said first body portion.

4. A coaxial connector in accordance with claim 1 in which said second portion of said body has a hollow lead receiving portion for receiving said one of said resistor leads with said lead receiving portion being staked to said one resistor lead to provide mechanical and electrical interconnection therebetween.

5. A coaxial connector in accordance with claim 1 in which said first body portion includes a retaining lip which is bent over said insulator to retain it within said first body portion.

6. A coaxial connector in accordance with claim 1 in which a portion of said first body portion is threaded and including a removable thread protector fitted over said second body portion and said threaded portion of said first body portion.

7. A coaxial connector in accordance with claim 4 wherein said hollow lead receiving portion has a sealed end whereby the coaxial connector is waterproof. 

1. A coaxial connector for use in a signal distribution system of the type having a transmission line extending from a directional tap housing with the tap housing mounting a plurality of coaxial connectors each of which is capable of being coupled to a transmission line, the coaxial connector comprising a body having a hollow first portion, a hollow second portion and an interface portion integral with and joining said second portion to said first portion, said interface portion being formed of material substantially thinner than said first and second body portions, a spring contact, an insulator surrounding said spring contact, said insulator and spring contact being disposed within said hollow first portion of said body, a terminating resistor having a pair of leads, said terminating resistor disposed within said hollow second portion of said body and one of said pair of leads being electrically connected to said second portion of said body and the other of said pair of leads extending into and being electrically connected to said spring contact.
 2. A coaxial connector in accordance with claim 1 wherein said interface portion of said body has an indentation formed therein for facilitating rupture of said interface portion in response to mechanical deflection of said second portion of said body to separate said second body portion from said first body portion.
 3. A coaxial connector in accordance with claim 1 wherein said interface portion of said body has a notch formed therein for facilitating rupture of said interface portion in response to mechanical deflection of said second portion of said body to separate said second body portion from said first body portion.
 4. A coaxial connector in accordance with claim 1 in which said second portion of said body has a hollow lead receiving portion for receiving said one of said resistor leads with said lead receiving portion being staked to said one resistor lead to provide mechanical and electrical interconnection therebetween.
 5. A coaxial connector in accordance with claim 1 in which said first body portion includes a retaining lip which is bent over said insulator to retain it within said first body portion.
 6. A coaxial connector in accordance with claim 1 in which a portion of said first body portion is threaded and including a removable thread protector fitted over said second body portion and said threaded portion of said first body portion.
 7. A coaxial connector in accordance with claim 4 wherein said hollow lead receiving portion has a sealed end whereby the coaxial connector is waterproof. 